Same reason why Dunkin runs out of bagels. They make or order x amount, and hope they last until the next order comes in.
The bodyguard is an abortion of a gun. The Sigma series (though I hate them) was a great idea. An inexpensive no thrill gun that will get you hooked to shooting. The Sigma was the first gun for many shooters I know.
If you think S&W is the only gun manufacturer that cares about cutting costs and profit margins, you have a lot to learn.
the new Sigmas are supposedly a lot better including a crisper trigger. I find it funny they have to pay Glock $10 every one they sell.